Mercury switch relay



Aug. 13, 1946. E. G. HENRY MERCURY SWITCH RELAY Filed Nov. 18, 1942 Patented Aug. 13, 1946 MERCURY SWITCH RELAY Earle G. Henry, Wilmette, Ill., assignor to Buckley Music System, 'Inc., a corporation of Illinois Application November 18, 1942, Serial No. 465,989

2 Claims.

The present invention relates to relays in which one or more mercury switches are oscillated to make and break circuits, upon the energization and de-energization of an operating electric magnet. Any conventional electromagnet, if powerful enough to do its work at all, tends to act suddenly. Consequently, such an electromagnet serving as an actuator for an oscillatory mercury switch, produces a correspondingly rapid swinging movement of the switch; the result being that the mercury is caused to oscillate relatively to its container and thus repeatedly open and close the circuit which it was intended either to open or to close.

The primary object of the present invention is to produce a simple and novel construction which will overcome the fault just mentioned and insure that a circuit will be opened or closed positively upon the operation of an oscillatory mercury switch.

My invention has for a further object to sim- 'plify the construction of mercury switch relays and make them sturdy and durable as well as effective and efficient in operation.

A further object of the present invention is to provide simple and novel means for holding capsule-like mercury switches in a relay structure or the like, so that they may be easily removed and replaced and be adapted to be turned end for end and be accurately located and securely held when inserted in the relay structure.

The various features of novelty whereby my invention is characterized will hereinafter be pointed out with particularity in the claims; but. for a full understanding of my invention and of its objects and advantages, reference may be had to the following detailed description taken in connection with the accompanying drawing, wherein:

Figure 1 is a top plan view of a relay embodying the present invention; Fig. 2 is a section on line 22 of Fig. l, the counter-balancing weight being shown in elevation; Fig. 3 is a front view of the device, a fragment of the retaining plate for the switches being broken away; Fig. 4 is a rear view of the device; Fig. 5 is a section through the cradle and one of the switches at the longitudinal axis of the switch; and Fig. 6 is a secof the pan, to provide three-point bearing against a wall to which the base may be fastened with its open side toward the wall. A pair of horizontal arms 3 are fixed to opposite sides of the base and project forwardly therefrom. Between these arms or brackets is mounted a cradle that is adapted to rock about a horizontal aXis parallel with the front face of the base in opposite directions from a horizontal plane. The cradle may conveniently be formed of a fiat piece of sheet metal that is square or retcangular and is provided at its four edges with flanges or wings; those at the sides being indicated at 5 and those at the front and rear at 6 and l. The side flanges and the rear flange are bent upwardly whereas the front flange is bent downwardly. A little trunnion 8 projects outwardly from each of the side flanges and through an opening in the adjacent supporting bracket or arm 3. Fastened to the bottom of the cradle, toward opposite sides, are a pair of stiff arms 9. Another stiff arm H3, lying flat against the under side of the cradle, is fastened thereto and projects rearwardly through a window H in the front wall of the base. The rear end of the arm or stem Ill may be bent upwardly, within the base, as indicated at l2}.

- Resting loosely on the part I2 is a fairly massive tion on line B6 of Fig. 2, showing only a frag- I ment of the cradle and one of the switches.

Referring to the drawing, I represents a base which is conveniently in the form of a shallow. sheet metal, rectangular pan. Within the pan are three feet 2 distributed in the form of a triangle and somewhat longer than the depth weight 24 held in the pan by a pair of vertical guides l5 which leave the weight freedom of up and down movements.

Projecting forwardly from the longitudinal center of the base, below the cradle, is a heavy bar or plunger I6 of magnetic material; connection with the base being a hinge that permits swinging movements in a vertical plane, preferably through a limited angle only. In the arrangements shown, the front wall of the base is provided with a hole through which the short flange of an L-shaped plate I! projects; the long flange or arm of the plate lying against and being welded to the rear side of this wall. The rear end of the member !6 is slotted to receive the forwardly projecting flange and is secured to the latter by a hinge pin l8. It will be seen that the rear end of the member l6 extends quite close to the long arm of the supporting plate I! which, therefore, serves as a stop to limit swinging movements in both directions.

Cooperating with the member IE is a massive electromagnet l9 surrounded by a heavy iron shell 20. The electromagnet has a central bore in which the member i6 is a good sliding fit, this member forming an armature or plunger device for the electromagnet. There is the usual plug 2| of electromagnetic material fixed in the forward end of the bore in the electromagnet, and this plug may be caused to strike against the forward end of the plunger member to limit the rearward travel of the electromagnet and thus serve as the actual stop for this purpose. The electromagnet is connected to the arms 9 by means of short pins or trunnions 22 fixed to the shell of the electromagnet and extending through holes in the lower ends of the arms. Consequently when the electromagnet is energized and moved toward the base it rocks the cradle and lifts the weight M. Then, upon deenergizing the electromagnet, the weight M restores the parts to the positions illustrated in Fig. 2.

The cradle serves to support any desired number of mercury switches of the type that are adapted to open and close by means of such rocking movements as can be provided by the cradle. To this end the cradle is equipped with holders for as many switches as are needed. In order to permit all of the switches to be simultaneously opened or closed or to permit some of them to open at the time that others are closing, I so construct the holders that any switch may be turned end for end so that the same rocking movement of the cradle may serve both to open and to close the same switch, depending upon which end is forward which end is toward the rear.

The switches illustrated are of the capsule type indicated as a whole at 2'5, one end of each capsule or casing being smaller in diameter than the other end. Each holder consists of two U- shaped clips 25, of resilient sheet metal, secured in alignment with each other, one behind and one in front of the axis about which the cradle rocks. Each clip is secured to the cradle by two rivets 25 along the longitudinal center line; the heads of the rivets projecting up into the clips to form bearings which are engaged by the under side of the large end of a capsule as shown in 'g. 5. Each clip has in one of the sides adjacent to the top, and midway between the ends, a rounded inward projection 2'5 that bears upon the large end of the capsule, somewhere in the upper half of the latter. By this means the large end of the capsule is provided with a threepoint hearing which accurately aligns it. Although the small end of the capsule extends through a clip, it has no bearing in the same as long as it is properly held by its large end. Upon turning a switch end for end the clip which was previously idle becomes the active one.

It will be seen that the cradle is so proportioned that the rear ends of the switches may engage with the rear flange 'a', while the front ends may be engaged by a retaining plate 28 lying flat against and secured to the flange at the front end of the cradle. The plate 28 may conveniently be held in place by screws 23 extending through vertically elongated slots 33 into the flange 5. Theslots are made long enough so that, upon loosening the screws, the retaining plate may be dropped down clear of the switches, without completely detaching the plate from the cradle.

The side walls or flanges of the cradle are carried a considerable distance above the tops of the switches so as to provide room above the switches for a rod til extending transversely across the cradle and supported at its ends by these sides or flanges. The rod is preferably sheathed with insulating material 32. The flex- 4 ible cords 33, containing the conductors that are connected to the switches, are carried from one side of the rod 3i and underneath the same to the switch terminals, so as to insure against the creation of sharp bends in the cords when the cradle is rocked.

When a mercury switch is rocked suddenly from one position to another, there is a surging of the mercury back and forth before a stable condition is reached. By my improved construction, I prevent this sudden shifting of the switches which the powerful electromagnets tend to cause. This improved action results from the inertia of the masses that must be moved. Part of the inertia is provided by the weight it, which I use in lieu of the usual springs, but the greater part is afforded by the electromagnet itself which is purposely made massive. As a result of this construction, the elect-romagnet starts slowly when energized and, when deenergized, likewise aids in producing a slowly starting return movement.

I have also found that the position of the rocking relative to the body of mercury, affects the tendency to surge on the part of the mercury and that the least amount of surging occurs when this axis is in the vicinity of the center of gravity of the movable body of mercury. In the particular switch illustrated, the inner shell as of the capsule is metal and forms one electrode, while the other electrode 35 is a button or disk at the longitudinal center of the switch within the large end of the capsule and nearer to the inner end than to the outer end of the enlarged part of the capsule. It will be seen that the axis of the trunnions 8 of the cradle, upon which it rocks, is about midway between the ends of the capsule and intersects the longitudinal axis of the latter. Therefore, in this particular form of switch, the shifting body 323 of mercury lies wholly on one side of the rock- I ing axis of the cradle when the switch is open as in 5; and when the switch is rocked in the counter-clockwise direction, so as to bring the mercury into the other end of the switch, the center of gravity of the movable body of mercury is approximately at the axis about which the oracle rocks. It is immaterial whether the switch is positioned in the cradle as in Fig. 5 or is turned end for end, because the cradle rocks through equal angles above and below a horizontal position; and, as a result, if the switch in Fig, 5 were turned end for end, the movable body of mercury would be in the same position with respect to the rocking axis, when the switch is closed, as it is with the disposition of parts illustrated in Fig. 5. The limits of the rocking movements are always the same, the rocking movement in one direction always ceasing when the armor tail piece it strikes the edge of the bottom of the window ii, whereas the cradle can swing in the opposite direction only until the plug 25 strikes the end of the plunger l6.

It will thus be seen that I have produced a simpl novel mercury switch electromagnetic relay to insure that a circuit once closed,

remains closed until the relay is operated for the purpose of closing the same, thereby preventing chattering or repeated opening and closing of a switch due to undesirable movements of the mercury; that switches may easily be removed replaced; and that any switch in a group thereof may easily be turned end for end to cause it to close when the others open.

While I have illustrated and described with particularity only a single preferred form of my invention, I do not desire to be limited to the exact structural details thus illustrated and described; but intend to cover all forms and arrangements which come within the definitions of my invention constituting the appended claims.

I claim:

1. In an electromagnetic switch device, an upright base, a cradle for a mercury switch mounted on the front side of the base for rocking 10 movements above a horizontal axis parallel to the base, a weight cooperating with the cradle to swing it in one direction, a solenoid below and hinged to the cradle, and a core of magnetic material hinged at one end to the base and extending at the other end into the solenoid to cause the solenoid to be drawn toward the base and the cradle to be rocked in the direction opposite to the aforesaid direction when the solenoid is energized, the hinge axes of the solenoid and core being so disposed that the solenoid and core remain coaxial during shifting movements of the solenoid along the core.

2. A device as set forth in claim 1, wherein the hinge axis of the solenoid is parallel to the axis about which the cradle rocks and passes through the center of gravity of the solenoid.

EARLE G. HENRY. 

